Income Taxes - Deferred Income Taxes (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Operating Loss Carryforwards [Line Items]
Total deferred income tax assets	$ 91,680	$ 88,176
Valuation allowance	(2,160)	(3,288)
Deferred tax assets, net of valuation allowance	89,520	84,888
Deferred tax liabilities, gross	16,521	16,897
Deferred tax liabilities, net	16,521	16,897
Depreciation and amortization
Operating Loss Carryforwards [Line Items]
Total deferred income tax assets	0	0
Deferred tax liabilities, gross	3,450	3,562
Share-based compensation
Operating Loss Carryforwards [Line Items]
Total deferred income tax assets	451	959
Deferred tax liabilities, gross	0	0
Accruals and prepaids
Operating Loss Carryforwards [Line Items]
Total deferred income tax assets	6,586	6,806
Deferred tax liabilities, gross	0	0
Bad Debts
Operating Loss Carryforwards [Line Items]
Total deferred income tax assets	2,727	2,594
Deferred tax liabilities, gross	0	0
Acquired intangible assets
Operating Loss Carryforwards [Line Items]
Total deferred income tax assets	0	0
Deferred tax liabilities, gross	13,071	13,335
Net operating loss carryforwards
Operating Loss Carryforwards [Line Items]
Total deferred income tax assets	33,247	27,607
Deferred tax liabilities, gross	0	0
Tax credit carryforwards
Operating Loss Carryforwards [Line Items]
Total deferred income tax assets	48,669	50,210
Deferred tax liabilities, gross	$ 0	$ 0